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<h1><img src = ".\img\fx_iwa_spectrum.png" width = 30 height = 30 >   SpectrumFx Iwa</h1>

<h4>● Overview</h4>
This effect produces a rainbow pattern like that of a thin film interference, according to the brightness<br>
of the input image.<br>
Even though the rainbow colors generated are not actually a thin film interference, similar results to<br>
a glare material can be obtained.

  <h4>● Input port</h4>
<UL>
<LI><b>Source</b> : Connect the source image. The brightness of the source image, corresponds to the<br>
thickness of the thin film.<br>
The brighter the luminosity, the thinner the film thickness will be. A luminosity of 0.0 corresponds to<br>
"Thickness Min" described later, and a luminosity of 1.0 corresponds to "Thickness Max".</LI>
<LI><b>Light</b> : Connect the light image.<br>
When a light image is connected, the output results are as follows:</LI>
<UL>
<LI>The Alpha channel of the output result is replaced with the alpha channel of the Light image.</LI>
<LI>If the "Light Threshold" parameter described below is enabled, the Light image and the generated<br>
rainbow can be combined and output on the screen.</LI>
</UL>
</UL>

<h4>● Parameters</h4>
<UL>
<LI><b>Intensity</b> : The light intensity. The higher the value, the brighter the rainbow.</LI>
<LI><b>Refractive Index</b> : The refractive index of the medium. The higher the value, the brighter the<br>
rainbow.</LI>
<LI><b>Thickness Max</b> : Maximum thickness of the thin film. Corresponds to the film thickness of the<br>
low luminance portion of the Source image.</LI>
<LI><b>Thickness Min</b> : Minimum thickness of the thin film. Corresponds to the film thickness of the<br>
high luminance part of the Source image.</LI>
*Thickness can also take a negative value. In that case, all parts where the film thickness is negative<br>
are calculated as zero.<br>
*Thickness Min and Max can be reversed. In that case, the iridescent pattern will be reversed.
<LI><b>R/G/B Gamma</b> : Gamma correction value for each RGB channel of the rainbow pattern.</LI><br>
<LI><b>Lens Factor</b> : A gamma correction value that can be added when outputting a rainbow pattern from<br>
the luminosity of the Source image.<br>
This allows, for example, concentric patterns to be distorted through a convex / concave lens in the<br>
iridescent period.</LI>
<LI><b>Light Threshold</b> : When a Light image is connected, the Light image can be combined with the<br>
rainbow pattern on the screen.<br>
Light Threshold is the minimum Alpha channel value of the Light image required for screen composition.<br>
For each pixel, the following processing will be performed:</LI>
<UL>
<LI>When the alpha channel of the Light image is below the Light Threshold: Screen composition is not<br>
performed.</LI>
<LI>When the alpha channel of the Light image is 1: The Light image is composited on the screen at 100%.</LI>
<LI>When the alpha channel of the Light image is greater than the Light Threshold but less than 1: The<br>
screen composition ratio will be linearly interpolated.</LI>
</UL>
The smaller the Light Threshold value, the larger the screen ratio with the Light image, so the output<br>
image will be brighter. It can also accept negative values.
</UL>
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